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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF ALTERNATIVE PRACTICES FOR IMPROVED WATERSHED MANAGEMENT

Location: Cropping Systems and Water Quality Research

Title: Adsorption of Isoxaflutole Degradates to Hydrous Metal Oxide Surfaces

Authors
item Goyne, Keith -
item Wu, Si Hyun -
item Lerch, Robert
item Lin, Chung Ho -

Submitted to: Clay Minerals Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2009
Publication Date: June 5, 2009
Citation: Goyne, K.W., Wu, S., Lerch, R.N., Lin, C. 2009. Adsorption of Isoxaflutole Degradates to Hydrous Metal Oxide Surfaces [abstract]. Clay Minerals Society Meeting, June 5-11, 2009, Billings, Montana. p. 91.

Technical Abstract: Isoxaflutole (IXF) is a pre-emergence herbicide that is rapidly transformed to a more stable and soluble diketonitrile degradate (DKN) after field application and, subsequently, DKN can be degraded to a benzoic acid derivative (BA) within soil. Due to the short half-life (t1/2) of IXF and the significantly longer t1/2 of its degradation products, DKN and BA are be more prone to migration through soil to water resources than IXF. However, very little research has been conducted to investigate DKN and BA sorption to soil minerals. The primary objective of this research is to determine if DNA and BA are readily adsorbed by variable charged minerals and to elucidate the mechanism(s) through which DKN or BA interact with variable charged mineral surfaces. Both DKN and BA were adsorbed by hydrous aluminum and iron oxides (HAO and HFO, respectively), and slight hysteresis is observed between the adsorption and desorption isotherms of DKN reacted with HAO. Adsorption and desorption isotherms were generally well fitted by the Freundlich isotherm model. Adsorption edge experiments demonstrate a significant decrease in DKN and BA adsorption as a pH is increased, presumably due to unfavorable electrostatic interactions between the IXF degradates and dissociated surface functional groups on the mineral surface at higher pH values. Diffuse reflectance Fourier transformed infrared (DRIFT) spectra and attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectra suggest that DKN and BA interact with the mineral surfaces through electrostatic interactions, as no major shifts in spectra features are noted. This study demonstrates that DKN and BA can be adsorbed onto the surfaces of HAO and HFO and the mechanism of adsorption is primarily electrostatic interaction.

Last Modified: 8/22/2014
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